A flow battery is a battery in which a redox couple (mediator) is reacted, and it is not a battery in which a reductant and an oxidant are directly reacted in at least one electrode.
A lithium semi-redox flow battery is disclosed in Patent Literature 1. The flow battery comprises a combination of the cathode of a redox flow battery and an anode that uses lithium as an active material, and the flow battery is able to regain a cathode active material by both of electrical charging and chemical oxidation caused by addition of an oxidant.
Patent Literature 1: Japanese Patent Application Laid-Open No. 2013-26142